This invention relates generally to rotary lawnmower decks and more specifically to a rotary mower deck constructed of double wall of molded polymeric materials.
In conventional rotary lawnmowers, the mower deck generally serves as a frame for the mower with the engine, handle, wheels and other accessories being attached to various portions thereof. Such decks typically include an upper mounting surface to which the engine is mounted. The output shaft of the engine extends through a central opening in the deck so as to enable the mower blade to be operatively secured thereto. The deck normally incorporates a shroud covering the rotating blade which serves to both restrict access to the blade and also to direct the flow of grass clippings to a discharge opening in the side of the deck. A protective shield or a grass catcher can be attached to the deck, covering the discharge opening.
Heretofore, such mower decks have been fabricated from metal such as by various stamping or casting techniques. In some cases the deck is formed from a multiplicity of pieces which must thereafter be secured together such as by welding. These decks are generally heavy and may require several stamping or machining operations to complete. As a result, these mower decks are relatively expensive to produce. Further, the use of metal results in increased overall weight for the mower thus requiring greater effort to be expended in operation thereof.
The mower deck of the present invention overcomes these disadvantages of the prior construction. The mower deck of the present invention is specifically designed to be fabricated as an integral one piece unit from a polymeric composition which offers advantages of light weight and low cost fabrication while maintaining the ruggedness and durability achieved with prior metal mower decks.
The mower deck of the present invention is constructed of double walls of high density polyethylene by means of a blow molding process. At the edges of the deck, the center opening and discharge opening, the double walls are joined together during the forming process. In addition, at several other locations, the double walls are joined together so as to increase the rigidity of the resulting structure. Where not molded together, a cavity is formed between the double walls by the blow molding operation. The cavity between the walls is filled with a pour in place polyurethane foam which bonds to the wall of the cavity. This foam further increases the rigidity of the deck as well as provides increased sound absorption. Additionally, because of the versatility of the molding process, it is possible to simultaneously integrally form the necessary structures for mounting of the engine, wheels, handle and other accessories which may be secured to the mower deck in a conventional manner.
Further objects, features and advantages of the invention will become apparent from a consideration of the following description and the appended claims when taken in connection with the accompanying drawings.